1. Field of the Invention
This invention relates to granulating and coating techniques and more particularly to techniques effective for use in the granulating, coating, drying, etc. of a powdery or granular material having a relatively minute particle diameter.
2. Related Art Statement
In general, as the granulation coating techniques of the type described, such an arrangement is thought of that a raw powdery or granular material as being an article to be coated and coating liquid as being a coating material are supplied from positions opposed to each other in a diameter direction of the apparatus, and drying air streams such as hot air are supplied from the underside thereof.
Now, in the aforesaid techniques, the article to be coated and the coating material collide against each other from the directions opposed to each other. Moreover, in this type of collision against each other from the opposed directions, due to the imbalance in flow-out forces of the article to be coated and of the coating material, one of the article and the coating material tends to become stronger in the force of collision than the other.
For this reason, for example, when the blow-out force of the coating material is stronger than that of the article, such disadvantages tend to occur that the coating material adheres to the opposed inner wall surface of the apparatus and is solidified thereon, or the article adheres to the coating material before the coating material is solidified, and is accumulated thereon.
Furthermore, there is a fear that such a disadvantage may occur that, due to the imbalance in the blow-out forces or blow-out flow rates, the coating liquid itself is turned into solid particles due to a so-called "spray-dry" phenomenon, without adhering onto the article to be coated.